332 A^IMONIA AND NITEIC ACID. 



but by facts. Hence it is quite indifferent to him, 

 whether the theory, or what he dignifies by that name, is 

 correct or not, as he does not regulate his proceeduigs in 

 accordance witli it. 



Many thousand farmers, who have not the remotest 

 conception of the nutrition of plants or the composition 

 of manures, apply guano, bone earth, and other maniu-es, 

 to their fields, Avith fully the same effect and mth even the 

 same skill as others who possess such information ; nor do 

 the latter derive any manifest advantage from their know- 

 ledge, because it is not of the right kind ; for example, 

 the chemical analysis of mamnres is rather calculated for 

 ascertaining their purity, and for determining their price, 

 than as a means for making us acquainted with their 

 effect upon land. 



In England bone earth was used and valued as a 

 maniu-e half a century before any idea was formed as to 

 what its operation was due ; and when afterwards the 

 erroneous theory was adopted that its effect depended 

 upon the nitrogenous gelatine which it contained, this 

 view did not exert the slightest influence upon its 

 employment. 



The farmer manured his field Avith bone earth, not on 

 account of its nitrogen, but because he wished to have 

 larger crops of corn and fodder, and because experience 

 told him that he could not expect them mthout bone 

 earth. 



^ An agricultural practice, fomided upon a simple ac- 

 quaintance with facts, without any idea of their nature, or 

 one based on the exliaustion of the land, may be conducted 

 by a person of very hmited intelhgence, nay, the most 

 ignorant man may be fitted for the purpose, by the mere 

 statement of facts to him. But a rational pursuit of agri- 

 culture, which, wdth the greatest economy of capital and 



